Preparation process of nickel-copper alloy biodegradable stent

Abstract

The invention relates to a preparation process of a nickel-copper alloy biodegradable stent, which comprises the following steps: pretreating the surface of a matrix, dipping a sample in zinc, preparing a hydrotalcite precursor, roasting and reducing the precursor, preparing a Ni-Cu (nickel-copper) alloy catalyst, synthesizing a medical nickel-copper alloy and self-healing polyurethane (PUDS), and preparing a medical nickel-copper alloy stent. A coprecipitation method and a substrate conductive treatment method are creatively combined, the prepared nickel-copper alloy material shows proper strength, toughness and biodegradability, and the nickel-copper alloy material has the advantages of being good in supporting force, longitudinal flexibility, recovery point performance, biodegradability and the like.

Description

Technical Field

[0001] The present invention relates to a preparation process of a nickel - copper alloy biodegradable stent. Background Art

[0002] As an innovative medical material, biodegradable stents are gradually attracting people's attention. Traditional vascular stents are mostly made of durable materials such as stainless steel, nickel - titanium alloy, and cobalt - chromium alloy, which are designed to maintain their structural integrity throughout the lifespan of an animal or human recipient. However, the long - term presence of these permanent stents in the body may cause complications such as inflammatory reactions and in - stent restenosis. Therefore, the research and development of biodegradable stents that can degrade naturally has become an important direction in the medical field.

[0003] As a potential biodegradable material, nickel - copper alloy has good mechanical properties and biocompatibility. It can gradually degrade in the body and be absorbed by the body, thus avoiding the problems that may be caused by long - term presence in the body. An ideal nickel - copper alloy biodegradable stent needs to have the following characteristics: (1) sufficient support force performance and corrosion resistance; (2) good biodegradability; (3) flexibility and compliance of the stent. Compared with the materials used to prepare stents in the past, the self - healing polyurethane (PUDS) synthesized in the nickel - copper alloy stent can gradually degrade in the body, avoiding the long - term complications that may be caused by the permanent presence of traditional metal stents in the body. At the same time, nickel - copper alloy has good biocompatibility, and the degradation products are harmless to the body within a controllable range. Nickel - copper alloy has both high support force and softness, which can meet the support requirements of the stent in the initial stage of implantation, and gradually reduce the mechanical properties during the degradation process to avoid long - term compression of the blood vessel wall. Summary of the Invention

[0004] In view of the above problems, the present invention provides a preparation process of a nickel - copper alloy biodegradable stent.

[0005] The preparation process of a nano - silicon - carbon composite anode material and the lithium - ion battery process provided by the present invention include: surface pretreatment of the substrate, zinc dipping of the sample, preparation of the hydrotalcite precursor, roasting and reduction treatment of the precursor, preparation of the Ni - Cu (nickel - copper) alloy catalyst, medical nickel - copper alloy, synthesis of self - healing polyurethane (PUDS), and preparation of the medical nickel - copper alloy stent.

[0006] Among them, step (2) zinc dipping of the sample The sample after surface pretreatment of step (1) is subjected to chemical zinc dipping treatment. The zinc dipping solution is a mixed solution of zinc oxide, NaOH, and a small amount of ferric chloride and potassium sodium tartrate. After zinc dipping, a zinc dipping layer appears on the substrate test piece; Step (3) preparation of the hydrotalcite precursor Weigh Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate) and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in deionized water; dropwise add the mixed metal salt solution into the Na2CO3 (sodium carbonate) solution through a dropping funnel; during the dropping process, dropwise add NaOH (sodium hydroxide) through a peristaltic pump; after the dropping is completed, continue stirring, let the obtained suspension stand, then filter by suction and wash several times with deionized water, and then perform drying; Step (4) Precursor calcination and reduction treatment Place the Ni~Cu~Mg~AlHT precursor prepared in step (3) in a muffle furnace and calcine it at a rate of a certain amount K·min -1 in an air atmosphere; after calcination, grind, tablet, crush, and sieve to obtain the prepared catalyst particles; Step (6) Preparation of medical nickel-copper alloy Put the matrix material pretreated in step (2) into a graphite crucible, then place the graphite crucible in a crucible resistance furnace to heat up. During the heating process, put the Ni~Cu alloy catalyst prepared in step (5) into a seepage mold; place the seepage mold in another crucible resistance furnace to heat up and then keep it warm. After it is completely melted and the seepage mold is kept warm, take out the seepage mold and the graphite crucible containing the alloy catalyst melt and pour it into the seepage mold, quickly cover the mold top cover and fill the mold with high-pressure air. After the pressure seepage is completed, take out the seepage product from the mold; Step (7) Synthesis of self-healing polyurethane (PUDS) Weigh PUC1 plasmid in a two-necked flask, add DMF (N,N-dimethylformamide), and stir to completely dissolve the polymer; then connect argon gas, add a mixed solution of DMF and DMSO (dimethyl sulfoxide) containing EDC (carbodiimide) and HOBt (1-hydroxybenzotriazole) to activate the carboxyl group under ice bath; after half an hour, add a DMF solution containing triethylamine and dimethylaminoethyl acrylate, react at room temperature in an argon atmosphere, precipitate the reaction solution with distilled water, filter and collect the white solid product; after vacuum drying, obtain a light brown solid product; Step (8) Preparation of medical nickel-copper alloy stent Cast the medical nickel-copper alloy prepared in step (6) into a mold, perform solution treatment on the alloy stent, and coat the self-healing polyurethane (PUDS) prepared in step (7) on the tissue of the stent; turn, mill, and grind the heat-treated stent, and then polish the surface of the stent to finally obtain a medical nickel-copper alloy stent.

[0007] Preferably, step (1) Matrix surface pretreatment After mechanically polishing the rough surface of the aluminum substrate, soak the substrate in an alkaline chemical agent. After soaking, immerse it in the pickling solution of dilute HNO3 at room temperature to remove the oxide film on the surface of the aluminum substrate. Step (2) Specimen zinc immersion After the surface of the specimen is pretreated in step (1), perform chemical zinc immersion treatment on it. The zinc immersion solution is a mixed solution of zinc oxide, NaOH, a small amount of ferric chloride, and sodium potassium tartrate. After zinc immersion, a zinc immersion layer appears on the substrate specimen. Step (3) Preparation of hydrotalcite precursor Weigh Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate), and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in deionized water. Drop the mixed metal salt solution into the Na2CO3 (sodium carbonate) solution drop by drop through a dropping funnel. During the dropping process, drop NaOH (sodium hydroxide) through a peristaltic pump. After the dropping is completed, continue stirring. Let the obtained suspension stand, then filter it by suction and wash it several times with deionized water, and then perform drying. Step (4) Calcination and reduction treatment of the precursor Place the Ni~Cu~Mg~AlHT precursor prepared in step (3) in a muffle furnace and calcine it in an air atmosphere. After calcination, grind it, press it into tablets, crush it, and sieve it to obtain the prepared catalyst particles. Step (5) Preparation of Ni~Cu alloy catalyst Wash the nickel-copper alloy precursor obtained in step (4). Under the condition of constant current, electroactivate the precursor. After electroactivation treatment, dry the nickel-copper alloy precursor. Step (6) Preparation of medical nickel-copper alloy Put the substrate material pretreated in step (2) into a graphite crucible, and then place the graphite crucible in a crucible resistance furnace to heat up. During the heating process, put the Ni~Cu alloy catalyst prepared in step (5) into a seepage mold. Place the seepage mold in another crucible resistance furnace to heat up and then keep it warm. After it is completely melted and the seepage mold is kept warm, take out the seepage mold and the graphite crucible containing the alloy catalyst melt and pour it into the seepage mold. Quickly cover the mold top cover and fill the mold with high-pressure air. After the pressure-maintaining seepage is completed, take out the seepage product from the mold. Step (7) Synthesis of self-healing polyurethane (PUDS) Weigh the PUC1 plasmid into a two-necked flask, add DMF (N,N-dimethylformamide), and stir to completely dissolve the polymer. Subsequently, connect argon gas, add a mixed solution of DMF and DMSO (dimethyl sulfoxide) containing EDC (carbodiimide) and HOBt (1-hydroxybenzotriazole), and activate the carboxyl group under an ice bath. After half an hour, add a DMF solution containing triethylamine and dimethylaminoethyl acrylate, react at room temperature in an argon environment, precipitate the reaction solution with distilled water, and filter to collect the white solid product. After vacuum drying, a light brown solid product is obtained. Step (8) Preparation of medical nickel-copper alloy stent Cast and mold the medical nickel-copper alloy prepared in step (6), perform solution treatment on the alloy stent, and coat the self-healing polyurethane (PUDS) prepared in step (7) on the tissue of the stent. Turn, mill, and grind the heat-treated stent, and then polish the surface of the stent to finally obtain a medical nickel-copper alloy stent.

[0008] Preferably, step (1) Substrate surface pretreatment Mechanically polish the rough surface of the aluminum substrate for 1 - 5 minutes, then immerse the substrate in a sodium hydroxide solution for 2 - 5 minutes for chemical degreasing. After immersion, place it in a pickling solution of dilute HNO3 at room temperature for 1 - 5 minutes to remove the oxide film on the surface of the aluminum substrate.

[0009] Adopting the present invention, the advantages are that through its polishing technology, the sodium hydroxide solution can more fully infiltrate the aluminum substrate, thereby improving the surface bonding strength and support force between the substrates and enhancing the overall performance of the composite material; the cleaning process can remove the oxide film on the surface of the aluminum substrate, making the substrate surface cleaner and smoother, which helps to extend the service life of the material.

[0010] Preferably, step (2) Specimen zinc dipping Perform chemical zinc dipping treatment on the specimen after the substrate surface pretreatment in step (1). The zinc dipping solution is a mixed solution of 50 - 70 g of zinc oxide, 60 - 300 g of NaOH, and 1 - 3 g of ferric chloride and potassium sodium tartrate. After zinc dipping for 10 - 15 s, a zinc dipping layer appears on the substrate specimen.

[0011] Adopting the present invention, the advantages are that through zinc dipping with a mixed solution of ferric chloride and potassium sodium tartrate, the interfacial adhesion performance between the fiber and the matrix material improves the interfacial adhesion performance of the matrix material, thereby changing the surface roughness of the fiber, which is beneficial to the preparation of medical alloy composite materials and improves the flexibility of the material.

[0012] Preferably, step (3) Preparation of hydrotalcite precursor Weigh 5 - 7 g each of Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate), and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in 100 - 150 mL of deionized water; dropwise add the mixed metal salt solution to 100 - 150 mL of Na2CO3 (sodium carbonate) solution through a dropping funnel; during the dropping process, use a peristaltic pump to dropwise add NaOH (sodium hydroxide) (2 - 3 M) to adjust the pH of the system to 10 ± 0.5; after the dropping is completed, continue stirring for 1 - 3 h, let the obtained suspension stand for 24 - 25 h, then filter by suction and wash with deionized water 3 - 4 times, and then dry at 370 - 375 K for 24 - 25 h.

[0013] Adopting the present invention, the advantages are that the preparation of the hydrotalcite precursor is beneficial to improving adhesion. The mixed metal salt solution of nickel nitrate reacts with the sodium carbonate solution, and at the same time, using a peristaltic pump to dropwise add NaOH (sodium hydroxide) to the treated material increases the surface activity of the precursor, which is beneficial to the subsequent calcination and reduction treatment of the precursor, and improves the stability of the alloy catalyst.

[0014] Preferably, in step (4), the precursor calcination and reduction treatment Place the Ni - Cu - Mg - Al HT precursor prepared in step (3) in a muffle furnace, and heat it from room temperature to 1073 - 1076 K at a rate of 3 - 6 K·min -1 in an air atmosphere, and calcine at 1073 - 1076 K for 4 - 5 h; after calcination, grind, tablet, crush, and sieve to obtain 30 - 60 g (diameter 0.3 - 0.6 mm) of catalyst particles.

[0015] Adopting the present invention, the advantages are that the precursor calcination and reduction treatment process is beneficial to the chemical reaction of the precursor in the preparation of the alloy catalyst. At the same time, calcination can effectively remove the organic substances in the precursor and avoid interference with subsequent reactions; it enhances the thermal stability and improves the catalytic activity. Grinding, tablet-making, crushing, and sieving can optimize the surface properties of the material, such as increasing the specific surface area and porosity, and improving the catalytic performance.

[0016] Preferably, in step (5), the preparation of the Ni - Cu alloy catalyst Wash the nickel - copper alloy precursor obtained in step (4) for 1 - 5 min, and electroactivate the precursor for 5 - 36 min under the condition of a constant current of 5 - 1000 mA·cm^ ~2 ; after electroactivation treatment, dry the nickel - copper alloy precursor for 1 - 5 min.

[0017] Adopting the present invention, the advantages are that the electroactivation of the nickel - copper alloy catalyst has a constant current of 5 - 1000 mA·cm^ ~2The conditions are conducive to adjusting the electronic structure of the material, enhancing the conductivity and catalytic activity, improving the recovery property of the medical nickel-copper alloy. Drying can thoroughly remove the moisture in the precursor, avoid the interference of moisture on subsequent reactions, and improve the material stability.

[0018] Preferably, in step (6), the preparation of the medical nickel-copper alloy Put the pretreated matrix material in step (2) into a graphite crucible, and then place the graphite crucible in a crucible resistance furnace and heat it up to 530 - 535 °C; during the heating process, put the Ni-Cu alloy catalyst prepared in step (5) into a seepage mold; place the seepage mold in another crucible resistance furnace and heat it up to 350 - 355 °C for insulation. After complete melting and the seepage mold is insulated, take out the seepage mold and the graphite crucible containing the alloy catalyst melt and pour it into the seepage mold, quickly cover the mold top cover and fill the mold with high-pressure air of 0.2 - 0.4 MPa, and keep the pressure for 4 - 6 minutes; after the seepage is completed, take out the seepage product from the mold.

[0019] Adopting the present invention, the advantages are that the graphite crucible has high-temperature stability, is resistant to high temperature and has good thermal conductivity, is suitable for high-temperature treatment of the matrix material, can uniformly heat the matrix material, and avoid the decline of the material support force and flexibility caused by local overheating or uneven temperature.

[0020] Preferably, in step (7), the synthesis of self-healing polyurethane (PUDS) Weigh 5 - 6 g of PUC1 plasmid into a 250 - 300 mL two-necked flask, add 20 - 30 mL of DMF (N,N-dimethylformamide), and stir to completely dissolve the polymer; then connect argon gas, add 20 - 30 mL of a mixed solution of DMF and DMSO (dimethyl sulfoxide) (volume ratio 1:1 - 1:2) containing 0.5 - 0.9 g of EDC (carbodiimide) and 0.6 - 1 g of HOBt (1-hydroxybenzotriazole), and activate the carboxyl group under ice bath; after 0.5 - 1 h, add 20 - 30 mL of a DMF solution containing 1 - 5 g of triethylamine and 0.5 - 1 g of dimethylaminoethyl acrylate, and react at room temperature for 23 - 24 hours in an argon atmosphere; precipitate the reaction solution with distilled water with pH = 3 - 4, filter and collect the white solid product; after vacuum drying for 70 - 75 hours, obtain a light brown solid product.

[0021] Adopting the present invention, the advantages are that introducing dynamic covalent bonds and connecting argon gas in the hard segment structure, these bonds can break and re-bind when subjected to external stimuli, thereby endowing the material with self-healing ability and helping to adjust the softness and degradability of the material.

[0022] Preferably, in step (8), the preparation of the medical nickel-copper alloy stent Cast the medical nickel - copper alloy prepared in step (6) into a mold, perform solution treatment on the alloy stent, and coat the self - healing polyurethane (PUDS) prepared in step (7) on the tissue of the stent; turn, mill, and grind the heat - treated stent for 1 - 5 minutes each, and then polish the surface of the stent for 1 - 5 minutes to finally obtain a medical nickel - copper alloy stent.

[0023] Adopting the present invention, the advantages are that through solution treatment, the surface bonding strength of the medical nickel - copper alloy stent can be strengthened more fully, improving the overall performance; the processes of turning, milling, and grinding the stent contribute to improving the service life, support force, and flexibility of the stent.

[0024] In summary, the present invention has the following beneficial effects: 1. Adopting the present invention, the advantages are that through its polishing technology, the sodium hydroxide solution can infiltrate the aluminum matrix more fully, thereby improving the surface bonding strength and support force between the matrices and enhancing the overall performance of the composite material; the cleaning process can remove the oxide film on the surface of the aluminum matrix, making the matrix surface cleaner and smoother, which helps to improve the service life of the material. 2. Adopting the present invention, the advantages are that through zinc immersion with a mixed solution of ferric chloride and potassium sodium tartrate, the interfacial adhesion performance between the fiber and the matrix material improves the interfacial adhesion performance of the matrix material, thereby changing the surface roughness of the fiber, which is beneficial for the preparation of medical alloy composite materials and improving the flexibility of the material. 3. Adopting the present invention, the advantages are that the preparation of the hydrotalcite precursor is beneficial for improving adhesion. The metal salt mixed solution of nickel nitrate reacts with the sodium carbonate solution, and at the same time, the treated material is dropped with NaOH (sodium hydroxide) using a peristaltic pump, which increases the surface activity of the precursor, is beneficial for subsequent precursor calcination and reduction treatment, and improves the stability of the alloy catalyst. 4. Adopting the present invention, the advantages are that the precursor calcination and reduction treatment process is beneficial for the chemical reaction of the precursor in the preparation of the alloy catalyst. At the same time, calcination can effectively remove the organic substances in the precursor, avoiding their interference with subsequent reactions; enhancing its thermal stability, improving catalytic activity, and grinding, tabletting, crushing, and sieving can optimize the surface properties of the material, such as increasing the specific surface area and porosity, and improving catalytic performance. 5. Adopting the present invention, the advantages are that the electro - activation constant current of the nickel - copper alloy catalyst is 5 - 1000 mA·cm^ ~2 The conditions are conducive to adjusting the electronic structure of the material, improving conductivity and catalytic activity; enhancing the recoverability of the medical nickel - copper alloy, and drying can completely remove the moisture in the precursor, avoiding the interference of moisture with subsequent reactions and improving the material stability. 6. The advantages of adopting the present invention are that the graphite crucible has high-temperature stability, is resistant to high temperatures and has good thermal conductivity, is suitable for high-temperature treatment of the matrix material, can uniformly heat the matrix material, and avoid the decline of the material's support force and flexibility caused by local overheating or uneven temperature. 7. The advantages of adopting the present invention are that dynamic covalent bonds and argon gas are introduced into the hard segment structure. These bonds can break and re-bond when stimulated by the outside world, thereby endowing the material with self-healing ability and helping to adjust the softness and degradability of the material. 8. The advantages of adopting the present invention are that through solution treatment, the surface bonding strength of the medical nickel-copper alloy stent can be strengthened more fully, and the overall performance can be improved; the processes of turning, milling, and grinding the stent help to improve the service life, support force, and flexibility of the stent. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a preparation process of a nickel-copper alloy biodegradable stent of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention. Without departing from the spirit and essence of the present invention, any modification or replacement of the methods, steps, or conditions of the present invention belongs to the scope of the present invention.

[0027] Unless otherwise specified, the technical means used in the examples are conventional means well-known to those skilled in the art. In addition, all component raw materials used in the examples are known commercially available products.

[0028] Example 1

[0029] Step (1) Pretreatment of the matrix surface The rough surface of the aluminum matrix is mechanically polished for 5 minutes and then immersed in a sodium hydroxide solution for 5 minutes for chemical degreasing. After immersion, it is placed in a pickling solution of dilute HNO3 at room temperature for 5 minutes to remove the oxide film on the surface of the aluminum matrix. Step (2) Zinc immersion of the sample The sample after the pretreatment of the matrix surface in step (1) is subjected to chemical zinc immersion treatment. The zinc immersion solution is a mixed solution of 70 g of zinc oxide, 300 g of NaOH, and 1 g of ferric chloride and potassium sodium tartrate. After zinc immersion for 15 s, a zinc immersion layer appears on the matrix specimen. Step (3) Preparation of the hydrotalcite precursor Weigh 7 g each of Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate), and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in 150 mL of deionized water; dropwise add the mixed metal salt solution to 150 mL of Na2CO3 (sodium carbonate) solution through a dropping funnel; during the dropping process, use a peristaltic pump to dropwise add NaOH (sodium hydroxide) (3M) to adjust the pH of the system to 10; after the dropping is completed, continue stirring for 3 h, let the obtained suspension stand for 25 h, then filter it by suction and wash it 3 times with deionized water, and then dry it at 375K for 25 h; Step (4) Precursor calcination and reduction treatment Place the Ni~Cu~Mg~AlHT precursor prepared in step (3) in a muffle furnace and heat it from room temperature to 1076K at a rate of 6K·min -1 in an air atmosphere, and calcine it at 1076K for 5 h; after calcination, grind, tablet, crush, and sieve it to obtain 60 g (diameter 0.6 mm) of catalyst particles; Step (5) Preparation of Ni~Cu alloy catalyst Wash the nickel-copper alloy precursor obtained in step (4) for 5 min; under the condition of a constant current of 100 mA·cm^ ~2 electroactivate the precursor for 36 min; dry the electroactivated nickel-copper alloy precursor for 5 min; Step (6) Preparation of medical nickel-copper alloy Put the matrix material pretreated in step (2) into a graphite crucible, and then place the graphite crucible in a crucible resistance furnace and heat it to 535°C; during the heating process, put the Ni~Cu alloy catalyst prepared in step (5) into a seepage mold; place the seepage mold in another crucible resistance furnace and heat it to 355°C for insulation. After complete melting and insulation of the seepage mold, take out the seepage mold and the graphite crucible containing the alloy catalyst melt and pour it into the seepage mold, quickly cover the mold top cover and fill the mold with 0.4 MPa of high-pressure air, and keep the pressure for 6 minutes; after seepage is completed, take out the seepage product from the mold; Step (7) Synthesis of self-healing polyurethane (PUDS) Weigh 6 g of PUC1 plasmid into a 300 mL two-necked flask, add 30 mL of DMF (N,N-dimethylformamide), and stir to completely dissolve the polymer. Subsequently, connect argon gas, add 30 mL of a mixed solution of DMF and DMSO (dimethyl sulfoxide) (volume ratio 1:2) containing 0.9 g of EDC (carbodiimide) and 1 g of HOBt (1-hydroxybenzotriazole) to activate the carboxyl group under an ice bath. After 1 h, add 30 mL of a DMF solution containing 5 g of triethylamine and 1 g of dimethylaminoethyl acrylate, and react at room temperature for 24 h in an argon atmosphere. Precipitate the reaction solution with distilled water at pH = 4, filter to collect the white solid product, and obtain a light brown solid product after vacuum drying for 75 h. Step (8) Preparation of medical nickel-copper alloy stent Cast the medical nickel-copper alloy prepared in step (6) into a mold, perform solution treatment on the alloy stent, and coat the self-healing polyurethane (PUDS) prepared in step (7) on the tissue of the stent. Turn, mill, and grind the heat-treated stent for 5 min each, and then polish the surface of the stent for 5 min to finally obtain a medical nickel-copper alloy stent.

[0030] Example 2

[0031] Step (1) Pretreatment of the substrate surface Mechanically polish the rough surface of the aluminum substrate for 4 min, then immerse the substrate in a sodium hydroxide solution for 4 min for chemical degreasing. After immersion, place it in a pickling solution of dilute HNO3 at room temperature for 4 min to remove the oxide film on the surface of the aluminum substrate. Step (2) Zinc dipping of the specimen Perform chemical zinc dipping treatment on the specimen after the substrate surface pretreatment in step (1). The zinc dipping solution is a mixed solution of 65 g of zinc oxide, 290 g of NaOH, and 1 g of ferric chloride and sodium potassium tartrate. After zinc dipping for 14 s, a zinc dipping layer appears on the substrate specimen. Step (3) Preparation of hydrotalcite precursor Weigh 7 g each of Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate), and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in 140 mL of deionized water. Gradually add the mixed metal salt solution drop by drop to 140 mL of Na2CO3 (sodium carbonate) solution through a dropping funnel. During the dropping process, adjust the pH of the system to 10 by dropping NaOH (sodium hydroxide) (3 M) through a peristaltic pump. After the dropping is completed, continue stirring for 2 h. Let the obtained suspension stand for 24.5 h, then filter it and wash it 3 times with deionized water, and then dry it at 374 K for 24.5 h. Step (4) Calcination and reduction treatment of the precursor The Ni-Cu-Mg-Al HT precursor prepared in step (3) was placed in a muffle furnace and heated from room temperature to 1075 K at a rate of 5 K·min -1 in an air atmosphere, and calcined at 1075 K for 5 h; after calcination, it was ground, pressed, crushed, and sieved to obtain 55 g of catalyst particles (diameter 0.6 mm); Preparation of Ni-Cu alloy catalyst in step (5) The nickel-copper alloy precursor obtained in step (4) was washed for 4 min; under the condition of a constant current of 95 mA·cm^ ~2 , the precursor was electro-activated for 36 min; the electro-activated nickel-copper alloy precursor was dried for 4 min; Preparation of medical nickel-copper alloy in step (6) The pretreated substrate material in step (2) was placed in a graphite crucible, and then the graphite crucible was placed in a crucible resistance furnace and heated to 534 °C; during the heating process, the Ni-Cu alloy catalyst prepared in step (5) was placed in a seepage mold; the seepage mold was placed in another crucible resistance furnace and heated to 354 °C for insulation. After complete melting and insulation of the seepage mold, the seepage mold and the graphite crucible containing the alloy catalyst melt were taken out and poured into the seepage mold, the mold top cover was quickly covered, and high-pressure air of 0.39 MPa was filled into the mold, and the pressure was maintained for 5 minutes; after seepage, the seepage product was taken out of the mold; Synthesis of self-healing polyurethane (PUDS) in step (7) Weighed 5.9 g of PUC1 plasmid into a 300 mL two-necked flask, added 29 mL of DMF (N,N-dimethylformamide), and stirred to completely dissolve the polymer; then argon was turned on, and 29 mL of a DMF and DMSO (dimethyl sulfoxide) mixture (volume ratio 1:2) containing 0.8 g of EDC (carbodiimide) and 0.9 g of HOBt (1-hydroxybenzotriazole) was added to activate the carboxyl group under ice bath; after 1 h, 29 mL of a DMF solution containing 4 g of triethylamine and 1 g of dimethylaminoethyl acrylate was added, and the reaction was carried out at room temperature for 23 h in an argon atmosphere; the reaction solution was precipitated with distilled water with pH = 4, and the white solid product was collected by filtration. After 74 h of vacuum drying, a light brown solid product was obtained; Preparation of medical nickel-copper alloy stent in step (8) The medical nickel-copper alloy prepared in step (6) was cast into shape, the alloy stent was solution-treated, and the self-healing polyurethane (PUDS) prepared in step (7) was coated on the tissue of the stent; the heat-treated stent was turned, milled, and ground for 4 min each, and then the surface of the stent was polished for 4 min, and finally a medical nickel-copper alloy stent was obtained.

[0032] Example 3

[0033] Step (1) Substrate surface pretreatment Mechanically polish the rough surface of the aluminum substrate for 3 min, then immerse the substrate in a sodium hydroxide solution for 3 min for chemical degreasing. After immersion, place it in a pickling solution of dilute HNO3 at room temperature for 3 min to remove the oxide film on the surface of the aluminum substrate; Step (2) Specimen zinc immersion Perform chemical zinc immersion treatment on the specimen after the substrate surface pretreatment in step (1). The zinc immersion solution is a mixed solution of 64 g of zinc oxide, 289 g of NaOH, 1 g of ferric chloride and sodium potassium tartrate. After zinc immersion for 13 s, a zinc immersion layer appears on the substrate specimen; Step (3) Preparation of hydrotalcite precursor Weigh 6.9 g each of Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate) and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in 139 mL of deionized water; slowly add the mixed metal salt solution drop by drop to 139 mL of Na2CO3 (sodium carbonate) solution through a dropping funnel; during the dropping process, adjust the pH of the system to 10 by dropping NaOH (sodium hydroxide) (3M) through a peristaltic pump; after the dropping is completed, continue stirring for 2 h, let the obtained suspension stand for 24.4 h, then filter by suction and wash 3 times with deionized water, and then dry at 373 K for 24.4 h; Step (4) Calcination and reduction treatment of the precursor Place the Ni~Cu~Mg~AlHT precursor prepared in step (3) in a muffle furnace, and heat it from room temperature to 1074 K at a rate of 4 K·min -1 in an air atmosphere, and calcine at 1074 K for 4.9 h; after calcination, grind, tablet, crush and screen to obtain 54 g (diameter 0.6 mm) of catalyst particles; Step (5) Preparation of Ni~Cu alloy catalyst Wash the nickel-copper alloy precursor obtained in step (4) for 4 min; under the condition of a constant current of 94 mA·cm ^~2 electroactivate the precursor for 35 min; dry the electroactivated nickel-copper alloy precursor for 3 min; Step (6) Preparation of medical nickel-copper alloy Put the matrix material pretreated in step (2) into a graphite crucible, and then place the graphite crucible in a crucible resistance furnace and heat it up to 533 °C; during the heating process, put the Ni-Cu alloy catalyst prepared in step (5) into a seepage mold; place the seepage mold in another crucible resistance furnace and heat it up to 353 °C for insulation. After complete melting and insulation of the seepage mold, take out the seepage mold and the graphite crucible containing the alloy catalyst melt and pour it into the seepage mold. Quickly cover the mold top cover and fill the mold with high-pressure air of 0.38 MPa, and keep the pressure for 5 minutes; after the seepage is over, take out the seepage product from the mold; Synthesis of self-healing polyurethane (PUDS) in step (7) Weigh 5.8 g of PUC1 plasmid into a 300 mL two-necked flask, add 28 mL of DMF (N,N-dimethylformamide), and stir to completely dissolve the polymer; then connect argon gas, add 29 mL of a mixed solution of DMF and DMSO (dimethyl sulfoxide) (volume ratio 1:1) containing 0.8 g of EDC (carbodiimide) and 0.9 g of HOBt (1-hydroxybenzotriazole), and activate the carboxyl group under ice bath; after 1 h, add 28 mL of a DMF solution containing 3 g of triethylamine and 1 g of dimethylaminoethyl acrylate, and react at room temperature for 23 hours in an argon atmosphere; precipitate the reaction solution with distilled water with pH = 4, filter and collect the white solid product; after vacuum drying for 73 hours, obtain a light brown solid product; Preparation of medical nickel-copper alloy stent in step (8) Cast and form the medical nickel-copper alloy prepared in step (6), perform solution treatment on the alloy stent, and coat the self-healing polyurethane (PUDS) prepared in step (7) on the tissue of the stent; turn, mill, and grind the heat-treated stent for 3 minutes each, and then polish the surface of the stent for 3 minutes to finally obtain a medical nickel-copper alloy stent.

[0034] Example 4

[0035] Pretreatment of the matrix surface in step (1) Mechanically polish the rough surface of the aluminum matrix for 4 minutes, then immerse the matrix in a sodium hydroxide solution for 4 minutes for chemical degreasing. After immersion, place it in dilute HNO3 acid pickling solution at room temperature for 4 minutes to remove the oxide film on the surface of the aluminum matrix; Zinc immersion of the sample in step (2) Perform chemical zinc immersion treatment on the sample after the matrix surface pretreatment in step (1). The zinc immersion solution is a mixed solution of 65 g of zinc oxide, 290 g of NaOH, and 1 g of ferric chloride and sodium potassium tartrate. After zinc immersion for 14 s, a zinc immersion layer appears on the matrix test piece; Preparation of hydrotalcite precursor in step (3) Weigh 7 g each of Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper(II) nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate), and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in 140 mL of deionized water; dropwise add the mixed metal salt solution to 140 mL of Na2CO3 (sodium carbonate) solution through a dropping funnel; during the dropping process, use a peristaltic pump to dropwise add NaOH (sodium hydroxide) (3 M) to adjust the pH of the system to 10 ± 0.5; after the dropping is completed, continue stirring for 2 h, let the obtained suspension stand for 24.5 h, then perform suction filtration and wash it 3 times with deionized water, and then dry it at 374 K for 24.5 h; Step (4) Precursor calcination and reduction treatment Place the Ni~Cu~Mg~AlHT precursor prepared in step (3) in a muffle furnace and heat it from room temperature to 1075 K at a rate of 5 K·min -1 in an air atmosphere, and calcine it at 1075 K for 5 h; after calcination, grind, press, crush, and sieve it to obtain 55 g (diameter 0.6 mm) of catalyst particles; Step (5) Preparation of Ni~Cu alloy catalyst Wash the nickel-copper alloy precursor obtained in step (4) for 4 min; under the condition of a constant current of 95 mA·cm^ ~2 electroactivate the precursor for 36 min; dry the electroactivated nickel-copper alloy precursor for 4 min; Step (6) Preparation of medical nickel-copper alloy Put the matrix material pretreated in step (2) into a graphite crucible, and then place the graphite crucible in a crucible resistance furnace and heat it to 534 °C; during the heating process, put the Ni~Cu alloy catalyst prepared in step (5) into a seepage mold; place the seepage mold in another crucible resistance furnace and heat it to 354 °C for insulation. After complete melting and insulation of the seepage mold, take out the seepage mold and the graphite crucible containing the alloy catalyst melt and pour it into the seepage mold, quickly cover the mold top cover and fill the mold with high-pressure air of 0.39 MPa, and keep the pressure for 5 minutes; after seepage is completed, take out the seepage product from the mold; Step (7) Synthesis of self-healing polyurethane (PUDS) Weigh 5.9 g of PUC1 plasmid into a 300 mL two-necked flask, add 29 mL of DMF (N,N-dimethylformamide), and stir to completely dissolve the polymer. Subsequently, connect argon gas, add 29 mL of a mixed solution of DMF and DMSO (dimethyl sulfoxide) (volume ratio 1:2) containing 0.8 g of EDC (carbodiimide) and 0.9 g of HOBt (1-hydroxybenzotriazole) to activate the carboxyl group under an ice bath. After 1 h, add 29 mL of a DMF solution containing 4 g of triethylamine and 1 g of dimethylaminoethyl acrylate, and react at room temperature for 23 h in an argon environment. Precipitate the reaction solution with distilled water at pH = 4, filter to collect the white solid product. After vacuum drying for 74 h, a light brown solid product is obtained. Step (8) Preparation of medical Ni-Cu alloy stent Cast the medical Ni-Cu alloy prepared in step (6) into a mold, perform solution treatment on the alloy stent, and coat the self-healing polyurethane (PUDS) prepared in step (7) on the tissue of the stent. Turn, mill, and grind the heat-treated stent for 4 min each, and then polish the surface of the stent for 4 min to finally obtain a medical Ni-Cu alloy stent.

[0036] Comparative Example 1

[0037] Step (1) Pretreatment of the substrate surface Mechanically polish the rough surface of the aluminum substrate for 1.1 min, then immerse the substrate in a sodium hydroxide solution for 1.1 min for chemical degreasing. After immersion, place it in a pickling solution of dilute HNO3 at room temperature for 1.1 min to remove the oxide film on the surface of the aluminum substrate. Step (2) Zinc immersion of the specimen Perform chemical zinc immersion treatment on the specimen after the substrate surface pretreatment in step (1). The zinc immersion solution is a mixed solution of 62 g of zinc oxide, 270 g of NaOH, and 1 g of ferric chloride and potassium sodium tartrate. After zinc immersion for 12 s, a zinc immersion layer appears on the substrate specimen. Step (3) Preparation of hydrotalcite precursor Weigh 5.9 g each of Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate), and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in 110 mL of deionized water. Gradually add the mixed metal salt solution drop by drop to 110 mL of Na2CO3 (sodium carbonate) solution through a dropping funnel. During the dropping process, adjust the pH of the system to 10 by dropping NaOH (sodium hydroxide) (3 M) through a peristaltic pump. After the dropping is completed, continue stirring for 1 h. Let the obtained suspension stand for 24.2 h, then filter by suction and wash 3 times with deionized water, and then dry at 372 K for 24.2 h. Step (4) Calcination and reduction treatment of the precursor The Ni-Cu-Mg-Al HT precursor prepared in step (3) was placed in a muffle furnace and heated from room temperature to 1074 K at a rate of 4 K·min -1 in an air atmosphere, and calcined at 1074 K for 4.2 h; after calcination, it was ground, tableted, crushed, and sieved to obtain 54 g of catalyst particles (0.6 mm in diameter); Preparation of Ni-Cu alloy catalyst in step (5) The nickel-copper alloy precursor obtained in step (4) was washed for 2 min; under the condition of a constant current of 94 mA·cm^ ~2 the precursor was electro-activated for 15 min; the electro-activated nickel-copper alloy precursor was dried for 2 min; Preparation of medical nickel-copper alloy in step (6) The pretreated substrate material in step (2) was placed in a graphite crucible, and then the graphite crucible was placed in a crucible resistance furnace and heated to 532 °C; during the heating process, the Ni-Cu alloy catalyst prepared in step (5) was placed in a seepage mold; the seepage mold was placed in another crucible resistance furnace and heated to 352 °C for insulation. After complete melting and insulation of the seepage mold, the seepage mold and the graphite crucible containing the alloy catalyst melt were taken out and poured into the seepage mold, the mold top cover was quickly covered and high-pressure air of 0.28 MPa was filled into the mold, and the pressure was maintained for 4 minutes; after seepage, the seepage product was taken out of the mold; Synthesis of self-healing polyurethane (PUDS) in step (7) Weighed 5.2 g of PUC1 plasmid into a 300 mL two-necked flask, added 22 mL of DMF (N,N-dimethylformamide), and stirred to completely dissolve the polymer; then argon was introduced, and 29 mL of a mixed solution of DMF and DMSO (dimethyl sulfoxide) (volume ratio 1:1) containing 0.8 g of EDC (carbodiimide) and 0.6 g of HOBt (1-hydroxybenzotriazole) was added to activate the carboxyl group under ice bath; after 1 h, 22 mL of a DMF solution containing 2 g of triethylamine and 1 g of dimethylaminoethyl acrylate was added, and the reaction was carried out at room temperature for 23 hours in an argon atmosphere; the reaction solution was precipitated with distilled water with pH = 3, and the white solid product was collected by filtration; after 72 hours of vacuum drying, a light brown solid product was obtained; Preparation of medical nickel-copper alloy stent in step (8) The medical nickel-copper alloy prepared in step (6) was cast into shape, the alloy stent was solution-treated, and the self-healing polyurethane (PUDS) prepared in step (7) was coated on the tissue of the stent; the heat-treated stent was turned, milled, and ground for 2 min each, and then the surface of the stent was polished for 2 min to finally obtain a medical nickel-copper alloy stent.

[0038] Comparative Example 2

[0039] Step (1) Substrate surface pretreatment Mechanically polish the rough surface of the aluminum substrate for 1 min, then immerse the substrate in a sodium hydroxide solution for 1 min for chemical degreasing. After immersion, place it in a pickling solution of dilute HNO3 at room temperature for 1 min to remove the oxide film on the surface of the aluminum substrate; Step (2) Specimen zinc immersion The specimen after substrate surface pretreatment in step (1) is subjected to chemical zinc immersion treatment. The zinc immersion solution is a mixed solution of 62 g of zinc oxide, 266 g of NaOH, and 1 g of ferric chloride and potassium sodium tartrate. After zinc immersion for 10 s, a zinc immersion layer appears on the substrate specimen; Step (3) Preparation of hydrotalcite precursor Weigh 5.8 g each of Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate), and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in 100 mL of deionized water; drop the mixed metal salt solution into 110 mL of Na2CO3 (sodium carbonate) solution drop by drop through a dropping funnel; during the dropping process, drop NaOH (sodium hydroxide) (3M) through a peristaltic pump to adjust the pH of the system to 10; after the dropping is completed, continue stirring for 1 h, let the obtained suspension stand for 24.1 h, then filter by suction and wash with deionized water 3 times, and then dry at 372 K for 24.1 h; Step (4) Calcination and reduction treatment of the precursor Place the Ni~Cu~Mg~AlHT precursor prepared in step (3) in a muffle furnace and heat it from room temperature to 1073 K at a rate of 4 K·min -1 in an air atmosphere, and calcine it at 1073 K for 4.1 h; after calcination, grind, press, crush, and sieve to obtain 50 g (diameter 0.6 mm) of catalyst particles; Step (5) Preparation of Ni~Cu alloy catalyst Wash the nickel-copper alloy precursor obtained in step (4) for 1 min; under the condition of a constant current of 94 mA·cm^ ~2 electroactivate the precursor for 10 min; dry the electroactivated nickel-copper alloy precursor for 1 min; Step (6) Preparation of medical nickel-copper alloy Put the matrix material pretreated in step (2) into a graphite crucible, and then place the graphite crucible in a crucible resistance furnace and heat it up to 531 °C; during the heating process, put the Ni-Cu alloy catalyst prepared in step (5) into a seepage mold; place the seepage mold in another crucible resistance furnace and heat it up to 351 °C for heat preservation. After complete melting and heat preservation of the seepage mold, take out the seepage mold and the graphite crucible containing the alloy catalyst melt and pour it into the seepage mold, quickly cover the mold top cover and fill the mold with high-pressure air of 0.22 MPa, and keep the pressure for 4 minutes; after the seepage is completed, take out the seepage product from the mold; Step (7) Synthesis of self-healing polyurethane (PUDS) Weigh 5.1 g of PUC1 plasmid into a 300 mL two-necked flask, add 22 mL of DMF (N,N-dimethylformamide), and stir to completely dissolve the polymer; then connect argon gas, add 28 mL of a mixed solution of DMF and DMSO (dimethyl sulfoxide) (volume ratio 1:1) containing 0.7 g of EDC (carbodiimide) and 0.6 g of HOBt (1-hydroxybenzotriazole), and activate the carboxyl group under ice bath; after 1 h, add 21 mL of a DMF solution containing 2 g of triethylamine and 1 g of dimethylaminoethyl acrylate, and react at room temperature for 23 hours in an argon environment; precipitate the reaction solution with distilled water with pH = 3, filter and collect the white solid product; after vacuum drying for 71 hours, obtain a light brown solid product; Step (8) Preparation of medical nickel-copper alloy stent Cast the medical nickel-copper alloy prepared in step (6) into shape, perform solution treatment on the alloy stent, and coat the tissue of the stent with the self-healing polyurethane (PUDS) prepared in step (7); turn, mill, and grind the heat-treated stent for 1 min each, and then polish the surface of the stent for 1 min to finally obtain a medical nickel-copper alloy stent.

[0040] Detection experiment comparison: Detect the nickel-copper alloy biodegradable stents obtained in Examples 1 to 4 and Comparative Products 1 and 2, and the specific detection methods are as follows: Recovery point performance test method When the temperature rises from the temperature of the cooling and easily softening state to a certain critical temperature, the stent returns to the designed shape, and this temperature is called the stent recovery point. The recovery point of the alloy medical internal stent should be at 25 °C ± 5 °C. The test method is to put the stent to be tested into a beaker containing physiological saline at °C, apply pressure to make it soften and deform. The deformation degree is controlled so that after the cross-section of the stent is compressed into an ellipse, the short axis length is approximately equal to half of the original outer diameter of the stent. Then, slowly add hot water above °C to the beaker, stir while heating the water, measure the water temperature with a thermometer, and at the same time observe the deformation of the stent, and remember the temperature when the stent quickly recovers the deformation. Take the arithmetic mean, and the value of the recovery point is accurate to °C.

[0041] Pressure test method At 25°C to 35°C, place the stent to be measured between two parallel plates, and gradually flatten the stent with a pressure testing machine. When the cross-section of the stent becomes oval and the minor axis of the ellipse is equal to half of the designed outer diameter of the stent, measure the distance between the two parallel plates with a ruler. The load shown on the pressure testing machine is the supporting force of the stent. The measurement unit of the supporting force is N, and the value is accurate to 0.5 N.

[0042] Longitudinal flexibility performance test method When the alloy stent supporting force shape memory alloy medical internal stent bends along the axis, the performance that the outer diameter of the bent part does not become smaller is called the longitudinal flexibility of the stent. The test method for the longitudinal flexibility of the stent is as follows: at room temperature of 25°C to 35°C, hold both ends of the stent and bend the stent, and measure the diameter at the bent part with a caliper. If the outer diameter at the bent part is not less than 75% of the outer diameter before bending, it can be regarded as the longitudinal flexibility of the stent being qualified.

[0043] Table 1 Test results of the recovery point performance

[0044] As can be seen from Table 1, Example 1 is the best and the comparative example is relatively poor. Due to different degrees of pretreatment of the material and the preparation of the hydrotalcite precursor, that is, by reacting a mixed solution of metal salts of different doses of nickel nitrate with sodium carbonate solution, and filtering and washing with deionized water, the interference to the material is reduced, the surface activity of the precursor is increased, the stability of the alloy catalyst is improved, which is beneficial to the subsequent preparation of medical nickel-copper alloy and electroactivation. The strength of the material is improved, and thus the recovery point performance of the stent is good.

[0045] Table 2 Test results of the pressure test

[0046] As can be seen from Table 2, regarding the supporting force of the stent, as the precursor is placed in a muffle furnace and calcined in an air atmosphere; after calcination, the electronic structure of the material is adjusted, the electron mobility is enhanced, and the conductivity and catalytic activity are improved. Furthermore, in the preparation of the medical nickel-copper alloy, the atomic binding force of the nickel-copper alloy is enhanced, thereby improving the strength of the material and the supporting force is increased. At the same time, drying can completely remove the moisture in the precursor and improve the stability of the nickel-copper alloy stent.

[0047] Table 3 Test results of the longitudinal flexibility performance

[0048] As can be seen from the results in Table 3, the longitudinal flexibility of Example 1 is the best. In the preparation of medical nickel-copper alloy, the graphite crucible has high-temperature stability, high temperature resistance and good thermal conductivity, which is conducive to high-temperature treatment of the matrix material, uniformly heating the matrix material, and avoiding the decrease of the material support force and flexibility caused by local overheating or uneven temperature, thus affecting the bending flexibility of the alloy stent.

[0049] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A process for preparing a nickel-copper alloy biodegradable stent, characterized in that: include: Substrate surface pretreatment, sample zinc immersion, hydrotalcite precursor preparation, precursor calcination and reduction treatment, preparation of Ni~Cu (nickel-copper) alloy catalyst, medical nickel-copper alloy, preparation of self-healing polyurethane (PUDS) synthesis, and preparation of medical nickel-copper alloy stents.

2. The process for preparing a nickel-copper alloy biodegradable stent according to claim 1, characterized in that: Step (1) Substrate surface pretreatment After the rough surface of the aluminum substrate is mechanically polished, the substrate is soaked in an alkaline chemical agent, and then placed in a pickling solution of dilute HNO3 at room temperature to erode it; the oxide film on the surface of the aluminum substrate is removed; Step (2) Zinc immersion of sample The sample after the substrate surface pretreatment in step (1) is subjected to chemical zinc immersion treatment, wherein the zinc immersion solution is a mixture of zinc oxide, NaOH and a small amount of ferric chloride and potassium sodium tartrate, and after zinc immersion, a zinc immersion layer appears on the substrate test piece; Step (3) Preparation of hydrotalcite precursor Weigh Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate) and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in deionized water; add the metal salt mixed solution drop by drop into the Na2CO3 (sodium carbonate) solution through a dropping funnel; during the dropping process, add NaOH (sodium hydroxide) drop by drop through a peristaltic pump; after the dropping is completed, continue stirring, let the obtained suspension stand, filter it, wash it with deionized water several times, and then dry it; Step (4) Precursor calcination and reduction treatment The Ni~Cu~Mg~AlHT precursor prepared in step (3) was placed in a muffle furnace and heated at a constant K·min in an air atmosphere. -1 After calcination, the catalyst is ground, tableted, crushed and sieved to obtain the prepared catalyst particles; Step (5) Preparation of Ni~Cu alloy catalyst The nickel-copper alloy precursor obtained in step (4) is cleaned; the precursor is electrically activated under constant current conditions, and the nickel-copper alloy precursor after the electrical activation treatment is dried; Step (6) Preparation of medical nickel-copper alloy The matrix material pretreated in step (2) is placed in a graphite crucible, and the graphite crucible is then placed in a crucible resistance furnace to heat up. During the heating process, the Ni-Cu alloy catalyst prepared in step (5) is placed in an infiltration mold; the infiltration mold is placed in another crucible resistance furnace to heat up and then kept warm. After the infiltration mold is completely melted and the infiltration mold is kept warm, the infiltration mold and the graphite crucible containing the alloy catalyst melt are taken out and poured into the infiltration mold, the mold top cover is quickly covered and high-pressure air is filled into the mold. After the pressure-maintaining infiltration is completed, the infiltration product is taken out from the mold; Step (7) Synthesis of self-healing polyurethane (PUDS) Weigh the PUC1 plasmid into a two-necked flask, add DMF (N, N-dimethylformamide), and stir to completely dissolve the polymer; then turn on argon gas, add a mixed solution of DMF and DMSO (dimethyl sulfoxide) containing EDC (carbonyl diimide) and HOBt (1-hydroxybenzotriazole), and activate the carboxyl group under ice bath; after half an hour, add a DMF solution containing triethylamine and dimethylaminoethyl acrylate, react at room temperature in an argon environment, use distilled water to precipitate the reaction solution, and filter to collect the white solid product; after vacuum drying, a light brown solid product is obtained; Step (8) Preparation of medical nickel-copper alloy stent The medical nickel-copper alloy prepared in step (6) is cast and molded, the alloy stent is subjected to solid solution treatment, and the self-healing polyurethane (PUDS) prepared in step (7) is coated on the tissue of the stent; the stent after heat treatment is turned, milled, and ground, and then the surface of the stent is polished to finally obtain a medical nickel-copper alloy stent.

3. The process for preparing a nickel-copper alloy biodegradable stent according to claim 1, characterized in that: Step (1) Substrate surface pretreatment The rough surface of the aluminum substrate is mechanically polished for 1 to 5 minutes, then immersed in a sodium hydroxide solution for 2 to 5 minutes for chemical degreasing. After immersion, it is etched in a pickling solution of dilute HNO3 at room temperature for 1 to 5 minutes to remove the oxide film on the surface of the aluminum substrate.

4. The process for preparing a nickel-copper alloy biodegradable stent according to claim 3, characterized in that: Step (2) Zinc immersion of sample The sample after the substrate surface pretreatment in step (1) is subjected to chemical zinc immersion treatment, wherein the zinc immersion solution is a mixture of 50-70 g zinc oxide, 60-300 g NaOH and 1-3 g of ferric chloride and potassium sodium tartrate. After zinc immersion for 10-15 seconds, a zinc immersion layer appears on the substrate test piece.

5. The process for preparing a nickel-copper alloy biodegradable stent according to claim 1, characterized in that: Step (3) Preparation of hydrotalcite precursor Weigh 5-7 g of Ni(NO3)2·6H2O (nickel nitrate), Cu(NO3)2·3H2O (copper nitrate trihydrate), Mg(NO3)2·6H2O (magnesium nitrate hexahydrate) and Al(NO3)3·9H2O (aluminum nitrate nonahydrate) and dissolve them in 100-150 mL of deionized water; add the metal salt mixed solution drop by drop into 100-150 mL of Na2CO3 (sodium carbonate) solution through a dropping funnel; during the addition, add NaOH (sodium hydroxide) (2-3 M) through a peristaltic pump to adjust the pH of the system to 10±0.5; after the addition is completed, continue stirring for 1-3 h, let the obtained suspension stand for 24-25 h, filter it and wash it with deionized water 3-4 times, and then dry it at 370-375 K for 24-25 h.

6. The process for preparing a nickel-copper alloy biodegradable stent according to claim 5, characterized in that: Step (4) Precursor calcination and reduction treatment The Ni~Cu~Mg~AlHT precursor prepared in step (3) was placed in a muffle furnace and heated at 3~6 K·min in an air atmosphere. -1 The rate is raised from room temperature to 1073~1076K, and calcined at 1073~1076K for 4~5h; after calcination, the catalyst particles are ground, pressed, crushed and sieved to obtain 30~60g (diameter 0.3~0.6mm).

7. The process for preparing a nickel-copper alloy biodegradable stent according to claim 6, characterized in that: Step (5) Preparation of Ni~Cu alloy catalyst The nickel-copper alloy precursor obtained in step (4) is cleaned for 1 to 5 minutes; at a constant current of 5 to 1000 mA·cm^ ~2 Under the above conditions, the precursor is electro-activated for 5 to 36 minutes, and the nickel-copper alloy precursor after electro-activation is dried for 1 to 5 minutes.

8. The process for preparing a nickel-copper alloy biodegradable stent according to claim 7, characterized in that: Step (6) Preparation of medical nickel-copper alloy The matrix material pretreated in step (2) is placed in a graphite crucible, and the graphite crucible is then placed in a crucible resistance furnace and heated to 530-535°C; during the heating process, the Ni-Cu alloy catalyst prepared in step (5) is placed in an infiltration mold; the infiltration mold is placed in another crucible resistance furnace and heated to 350-355°C for insulation; after the infiltration mold is completely melted and the infiltration mold is heat-insulated, the infiltration mold and the graphite crucible containing the alloy catalyst melt are taken out and poured into the infiltration mold, the mold top cover is quickly closed, and 0.2-0.4 MPa high-pressure air is filled into the mold and the pressure is maintained for 4-6 minutes; after the infiltration is completed, the infiltration product is taken out from the mold.

9. The process for preparing a nickel-copper alloy biodegradable stent according to claim 1, characterized in that: Step (7) Synthesis of self-healing polyurethane (PUDS) Weigh 5-6 g of PUC1 plasmid into a 250-300 mL two-necked flask, add 20-30 mL of DMF (N,N-dimethylformamide), and stir to completely dissolve the polymer; then turn on argon gas, add 20-30 mL of a mixture of DMF and DMSO (dimethyl sulfoxide) (volume ratio 1:1-1:2) containing 0.5-0.9 g of EDC (carbodiimide) and 0.6-1 g of HOBt (1-hydroxybenzotriazole), and activate the carboxyl group under ice bath; After 0.5~1h, add 20~30 mL of DMF solution containing 1~5g of triethylamine and 0.5~1g of dimethylaminoethyl acrylate, and react at room temperature in an argon environment for 23~24 hours; use distilled water with pH=3~4 to precipitate the reaction solution, and filter to collect the white solid product; after 70~75 hours of vacuum drying, a light brown solid product is obtained.

10. The process for preparing a nickel-copper alloy biodegradable stent according to claim 9, characterized in that: Step (8) Preparation of medical nickel-copper alloy stent The medical nickel-copper alloy prepared in step (6) is cast and molded, the alloy stent is subjected to solid solution treatment, and the self-healing polyurethane (PUDS) prepared in step (7) is coated on the tissue of the stent; the stent after heat treatment is turned, milled, and ground for 1 to 5 minutes each, and then the surface of the stent is polished for 1 to 5 minutes to finally obtain a medical nickel-copper alloy stent.

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